A large number of the collapse

landslides and debris flows at different scales triggered by Wenchuan Earthquake are great sources of sediment for the river in earthquake area. To study effects of earthquake erosion on sediment transportation after Wenchuan Earthquake

field investigation and measurements were performed for the landslides and avalanches on the Mianyuan River. Based on the data for the past 5 years

1.15×108 m3 deposits were produced during this earthquake equivalent to about 100 times of the amount of soil erosion for a normal year

most of which were deposited and accumulated in the tributary ditches or channels. It indicated that only a few part of fine sediments were transported to the downstream as suspended load

as the dominant coarse particles were over the transportation capacity of the rivers without distinct change of hydrological conditions during the last five years. Although earthquake erosion resulted in a huge amount of sediment in the upstream Mianyuan River

the annual sediment discharge had no obvious difference from that before the earthquake

which showed that the effects of sediment from earthquake erosion on sediment transportation in the lower Mianyuan and Tuojiang Rivers are limited in the short term.